/*
* Copyright (c) Microsoft Corporation. All rights reserved.
* Copyright (c) 2023 Huawei Device Co., Ltd.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file has been modified by Huawei to verify type inference by adding verification statements.
*/

// === tests/cases/compiler/thisConditionalOnMethodReturnOfGenericInstance.ts ===
declare function AssertType(value:any, type:string):void;
class A<T> {
    unmeasurableUsage!: {[K in keyof T]-?: T[K]};
}

class B<T> extends A<T> {
    method(): string | (this extends C ? undefined : null) {
AssertType("", "string");
        return "";
    }
}

class C<T = any> extends B<T> {
    marker!: string;
}

const x = new C<{}>();
AssertType(x, "C<{}>");
AssertType(new C<{}>(), "C<{}>");
AssertType(C, "typeof C");

const y = x.method(); // usage flags `method` in `B` as circular and marks `y` as the error-any type
AssertType(y, "union");
AssertType(x.method(), "union");
AssertType(x.method, "() => union");


